THE BRANCHIOPODA 



35- 



The last segment of the body, or telson, carries, except in 

 Limnetis and Thamnocephalus, a pair of furcal rami, long antenni- 

 form filaments in the Notostraca (Fig. 16), unsegmented styles or 

 flattened plates in the Anostraca (Fig. 20, C). In the Conchostraca 

 and Cladocera the posterior part of the body is flexed ventrally 

 and the furca is represented by a pair of strong curved claws 

 (Fig. 17, /). The anus opens either at the end of the body 



gn 



C. 



Fio. 20. 



A, head-region of Lcpidurus glacMis from below ; a', antennule ; ft", antenna ; gn, gnatho- 

 baso of first trunk-limb ; L, labrum or upper lip turned forwards (in the natural position it 

 covers the opposed edges of the mandibles) ; I, lower lip (according to Glaus, the inner lobes of 

 the maxillulae) ; m, mandible ; 7/ur', maxillula ; mx", maxilla. B, posterior end of body of 

 Lepidurus glacialis ; a, position of anal opening ; pi, supra-anal plate; r, rami of caudal fufca; 

 T, terminal segment or telson. C, posterior end of body of Branehitiecta pdLudosa ; letters as 

 above. (After Sars.) 



between the furcal rami or, in many Cladocera, some distance in 

 front on the dorsal surface. In the genera Lepidurus (Notostraca) 

 and Thamnocephalus (Anostraca) the telson is produced as a thin 

 plate above the anal opening (Fig. 20, B). 



Appendages. The antennules are, for the most part, purely 

 sensory in function, not segmented or obscurely so, and carrying 

 tufts of sensory filaments. In many Cladocera they are very small 

 and attached to the posterior surface of the deflexed beak-like 



